20989-19-9Relevant articles and documents
Chemical and Genetic Studies on the Formation of Pyrrolones During the Biosynthesis of Cytochalasans
Zhang, Haili,Hantke, Verena,Bruhnke, Pia,Skellam, Elizabeth J.,Cox, Russell J.
, p. 3106 - 3113 (2021/01/20)
A key step during the biosynthesis of cytochalasans is a proposed Knoevenagel condensation to form the pyrrolone core, enabling the subsequent 4+2 cycloaddition reaction that results in the characteristic octahydroisoindolone motif of all cytochalasans. In this work, we investigate the role of the highly conserved α,β-hydrolase enzymes PyiE and ORFZ during the biosynthesis of pyrichalasin H and the ACE1 metabolite, respectively, using gene knockout and complementation techniques. Using synthetic aldehyde models we demonstrate that the Knoevenagel condensation proceeds spontaneously but results in the 1,3-dihydro-2H-pyrrol-2-one tautomer, rather than the required 1,5-dihydro-2H-pyrrol-2-one tautomer. Taken together our results suggest that the α,β-hydrolase enzymes are essential for first ring cyclisation, but the precise nature of the intermediates remains to be determined.
Nucleophilic RhI Catalyzed Selective Isomerization of Terminal Aziridines to Enamides
Tian, Yingying,Kunz, Doris
, p. 4272 - 4275 (2020/07/04)
The selective isomerization of various terminal N-Boc protected aziridines to enamides was realized using the highly reactive nucleophilic rhodium catalyst C with the Lewis acid LiNTf2 as co-catalyst under moderate conditions. The reaction proceeds smoothly with only 1 molpercent catalyst loading and excellent yields were achieved. An intermediate containing an enamide with a non-conjugated terminal C=C double bond was detected during the course of the reaction, which isomerizes to form the thermodynamically favored 2-amido styrene. Mechanistic insight is gained based on these observations.
Synthesis of Water-Soluble Chiral DOTA Lanthanide Complexes with Predominantly Twisted Square Antiprism Isomers and Circularly Polarized Luminescence
Dai, Lixiong,Zhang, Junhui,Chen, Yuqing,Mackenzie, Lewis E.,Pal, Robert,Law, Ga-Lai
, p. 12506 - 12510 (2019/10/02)
One-step cyclization of a tetraazamacrocycle 5 with 70% yield in a 25-g scale was performed. Its chiral DOTA derivatives, L4, has ?93% of TSAP coordination isomer in its Eu(III) and Yb(III) complexes in aqueous solution. [GdL4]5- exhibits a high relaxivity, making it a promising and efficient MRI contrast agent. High luminescence dissymmetry factor (glum) values of 0.285 (ΔJ = 1) for [TbL3]- and 0.241 (ΔJ = 1) for [TbL4]5- in buffer solutions were recorded.
CHIRAL CYCLEN COMPOUNDS AND THEIR USES
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, (2018/04/13)
The present invention relates to the preparation of a series of chiral DOTA, D03A, D02A, DO1A, cyclen and their metal complexes, which display properties superior to those of previous DOTA- based compounds, and hence are potentially valuable as a platform for diagnostic applications. The chiral DOTAs reveal a high abundance of twisted square antiprism (TSA) geometry favoring them to be used as potential MRI contrast agents, whereas their rapid labelling properties at mild conditions make them excellent candidates for use as radiometal chelators.
Chiral ethylene-bridged flavinium salts: the stereoselectivity of flavin-10a-hydroperoxide formation and the effect of substitution on the photochemical properties
?urek, Ji?í,Svobodová, Eva,?turala, Ji?í,Dvo?áková, Hana,Svoboda, Ji?í,Cibulka, Radek
, p. 1780 - 1791 (2017/11/17)
A series of chiral non-racemic N1,N10-ethylene bridged flavinium salts 4 was prepared using enantiomerically pure 2-substituted 2-aminoethanols (R = isopropyl, phenyl, benzyl, 4-methoxybenzyl, 4-benzyloxybenzyl) derived from amino acids as the sole source of chirality. The flavinium salts were shown to form 10a-hydroperoxy- and 10a-methoxy-adducts with moderate to high diastereoselectivity depending on the ethylene bridge substituent originating from the starting amino acid. High diastereoselectivities (dr values from 80:20 to >95:5) were observed for flavinium salts bearing benzyl substituents attached to the ethylene bridge. The benzyl group preferred the face-to-face (syn) orientation relative to the flavinium unit; thereby effectively preventing nucleophilic attack from one side. This conformation was found to be the most stable according to the DFT calculations. Consequently, the presence of benzyl groups causes intermolecular fluorescence quenching resulting in a significant decrease in the fluorescence quantum yield from 11% for 4a bearing an isopropyl substituent to 0.3% for 4c containing a benzyl group and to a value lower than 0.1% for the benzyloxybenzyl derivative 4e.
NOVEL BENZODIOXANE-PIPERIDINE DERIVATIVES AND THEIR THERAPEUTIC APPLICATIONS FOR TREATING NEUROPSYCHIATRIC DISORDERS
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Paragraph 1249-1252, (2015/12/05)
The present invention concerns benzodioxane-piperidine with general formula I: wherein notably: R1 represents one or more identical or different substituent(s) on the benzene ring, each independently representing a hydrogen or halogen atom, or a C1-4 alkyl group, or a C1-4 alkoxy group or a C1-4 hydroxyalkyl group or a C1-4 alkylcarbonyl or an alkoxycarbonyl group or an OH group or an SO2R group with R alkyl, or a CN group, or a CF3 group, or an OCF 3 group; n=1, 2 or 3;m=0 or 1, andR2 represents one or more identical or different substituent(s) on the oxazolidinone or morpholinone ring, each independently representing: a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group, or a C1-4 hydroxyalkyl group, or an alkylcarbonyl group, or an alkoxycarbonyl group, or an alkoxyphenyl group.
Bioactive phenylalanine derivatives and cytochalasins from the soft coral-derived fungus, Aspergillus elegans
Zheng, Cai-Juan,Shao, Chang-Lun,Wu, Lu-Yong,Chen, Min,Wang, Kai-Ling,Zhao, Dong-Lin,Sun, Xue-Ping,Chen, Guang-Ying,Wang, Chang-Yun
, p. 2054 - 2068 (2013/07/26)
One new phenylalanine derivative 4′-OMe-asperphenamate (1), along with one known phenylalanine derivative (2) and two new cytochalasins, aspochalasin A1 (3) and cytochalasin Z24 (4), as well as eight known cytochalasin analogues (5-12) were isolated from the fermentation broth of Aspergillus elegans ZJ-2008010, a fungus obtained from a soft coral Sarcophyton sp. collected from the South China Sea. Their structures and the relative configurations were elucidated using comprehensive spectroscopic methods. The absolute configuration of 1 was determined by chemical synthesis and Marfey's method. All isolated metabolites (1-12) were evaluated for their antifouling and antibacterial activities. Cytochalasins 5, 6, 8 and 9 showed strong antifouling activity against the larval settlement of the barnacle Balanus amphitrite, with the EC50 values ranging from 6.2 to 37 μM. This is the first report of antifouling activity for this class of metabolites. Additionally, 8 exhibited a broad spectrum of antibacterial activity, especially against four pathogenic bacteria Staphylococcus albus, S. aureus, Escherichia coli and Bacillus cereus.
Electronic effects of aryl-substituted bis(oxazoline) ligands on the outcome of asymmetric copper-catalysed C-H insertion and aromatic addition reactions
Slattery, Catherine N.,O'Keeffe, Sarah,Maguire, Anita R.
, p. 1265 - 1275 (2013/11/19)
The effect of the modification of bis(oxazoline) ligands on the outcome of copper-catalysed C-H insertion and aromatic addition reactions is described. In general, these reactions display minimum sensitivity in terms of enantiocontrol to variation of the electronic properties of the aryl moiety of the ligand however, some influence is observed for C-H insertions employing naphthyl-substituted bis(oxazolines) and for aromatic addition reactions of biphenyl diazo ketone substrates. The synthesis of the modified bis(oxazolines), which include four novel structures, is also described.
Synthesis of l - Epi -capreomycidine derivatives via C-H amination
Tanino, Tetsuya,Ichikawa, Satoshi,Matsuda, Akira
, p. 4028 - 4031 (2011/10/04)
The l-epi-capreomycidine (Cpm) derivatives were efficiently and stereoselectively synthesized via nitrene C-H insertion starting from a readily available d-Tyr. Design of a substrate that takes into account hydrogen bonding is a critical feature in order
Catalyst-free aziridination and unexpected homologation of aziridines from imines
Branco, Paula Serio,Raje, Vivek Prabhakar,Dourado, Jorge,Gordo, Joana
scheme or table, p. 2968 - 2974 (2010/09/06)
Aziridination and unpredicted homologation reaction of N-sulfonylimines were achieved easily with a very simple, rapid and mild procedure through the use of diazomethane without the presence of any catalyst. The method represents an attractive alternative
